Radio today (Sept 1935-Dec 1936)

tory executives feel. Air leakage was one of the difficulties experienced in the early stages of metal-tube production. Such leakage troubles are now in hand, and are safeguarded against for customers' protection by holding back the tubes and re-testing them, thus giving a double-check on factory tests, before the tubes are shipped. Meanwhile, some receiver manufacturers, unable to get their requirements of the metal tubes, are shipping sets with mixed tube complements, filling in with both standard glass tubes and glass tubes with the new octal base. Glass vs. metal-tube costs * Against the metal tube is brought the complaint that it has unnecessarily increased the number of tube types required for the dealer's stock; also that the present higher prices of the metal tubes are raising the prices of radio sets to the public. Metal tubes are being furnished to set makers at prices nearly twice the cost of the familiar glass tube, and this has opened an opportunity for glass tubes with octal bases, which can be supplied at substantially lower prices. Similar differentials exist in the retail list prices of the various tubes offered for replacement. For example, the table shows the prices of glass, metal, and metal-glass equivalents. Tube Price to Retail No. Set Mfr. List Price 6A7 glass 38 cents $1.35 6A8 metal 70 cents 1.70 6A8g octal-glass ... 41 cents 1.70 0-42 glass 32 cents 1.10 6-P6 metal 60 cents 1.75 6-F6g octal-glass ... 35 cents 1.40 On an average receiver, it is claimed that the difference in cost of metal as against glass tubes may add $2.50 factory cost to the set, and that this item when carried to the retail purchaser at a multiplier of four, means an increase in retail cost of about $10 per set. Development expense — initial prices * Metal tube advocates point out that despite staggering amounts of money spent on metaltube development, some of the new metal-tube types are priced actually lower than were the corresponding glass tubes when originally introduced. Thus the 6A7 glass tube above cited first appeared at $2.20 list, in comparison with the initial metal price of $2 list. Similarly the 42 glass tube was originally priced at $2, in comparison with the initial price of the corresponding 6F6 metal at $1.75. More -or less -types * What will be the effect of the metal-tube program on retail tube stocks? In pre-metal days, the number of tubes needed was about 150 to meet all requirements. The metal line has added more. Since many a dealer sells only about 350 tubes a year, the necessity of carrying additional items puts a burden on the smaller merchant, driving tube business into hands of chain stores. On the other hand, behind the metal-tube program is the purpose to handle all future tube requirements with a small number of types, so that dealers' stocks will eventually be much simplified, say those pushing metal program. Redesign — neiv construction * Xew possibilities for tube construction are unfolding as the metal-tube plan develops, say engineers on the job. At present, all hands agree, any advantage in performance comes from the extra shielding which metal construction provides, and reduction in microphonics. Present internal construction follows closely old glass practice, but future models will be able to utilize metal envelope for radical redesign. Preliminary laboratory experiments are being made with a "metal-spray" sealing process to replace electrical welding of the outer envelope. By first heating the parts, and then flowing on metal from a spray-gun, the inventor thinks he has a cheaper substitute for electric welding. AUTOMOBILE-RADIO ACTIVE * The new policy of the automobile industry in bringing out its new models in October instead of at the first of the year, has brought new seasonal activity into the autoradio field as well. The increasingnumber of sets installed at the factory has resulted in large initial Fall orders which have speeded up some radio-set makers' auto-radio volume by 100 per cent or more. Latest word from Detroit also indicates that this Fall's auto radios give better reception and are more pleasing in appearance. Adoption of the steel roof by many of the automotive manufacturers has necessitated a change in the antenna system, as a result certain definite improvements have been incorporated. By using an antenna of the plate or strip type under each running board, ignition noise is reduced; in addition this type antenna does not respond well to frequencies higher than the broadcast band, thereby eliminating much of the high-frequency interference which formerly forced itself past the first detector and made its way into the output. The sensitivity of the receivers has been increased more than enough to compensate for the reduced antenna pick-up. Some of the receivers will give an output of one watt with an input of but a single microvolt. Improvements in filtering the ignition system and reduction of noise pickup by the antenna, as well as better receiver design, have made it possible to successfully employ this higher sensitivity. Reception at a distance is increased accordingly. Instead of the square, sharp-cornered cabinets, the Fall models are housed in cases of pleasing proportions and appearance with a definite leaning towards streamlining. Most of the automobiles are so designed that the controls become an integral part of the instrument panel. Efforts are being made to increase the frequency response of the speaker — the most notable being the use of the header speaker attached to the ceiling above the windshield. The high-frequency response is considerably increased. Experiments are being conducted using the dash and other parts of the car as a baffle. Other problems such as brake static, road static, tire static, antenna insulation are receiving much attention. Aside to FHA * The RMA, thinking of everything, has a definite feeling that the FHA should not stop at the wrong place in its financing radio sales. The manufacturers have, optimistically, applied for the further financing of receiving sets selling at $75 or more, which the FHA so far has avoided unless when the sets were built in. If the FHA allows refrigerators, argues the RMA, why not the more expensive radios? September, 1935 15